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The Future is Here: Memory Prosthetics

Developing implants that can restore damaged neural tissue – either by restoring the connections between damaged memory synapses or restoring cognitive function – is seen as the next great leap in prosthetic medicine. In recent years, steps have been taken in both areas, offering patients and willing subjects the option of restoring or hacking their neurology.

For example, last year, researchers working at the University of California and the University of Pennsylvania successfully managed to design and implement a brain implant that acted as a bypass for damaged brain tissue. This neural prosthesis successfully restored brain function in rats, demonstrating that the closed-loop brain-machine-brain interface could one day perform the same function in brain-damaged humans.

And as with many such projects, the Defense Advanced Research Projects Agency (DARPA) soon became involved, taking up the reins to fund the research and development of the technology. As part of the DARPA Restoring Active Memory (RAM) program, the device is currently being developed with the hope of restoring memory function in veterans who have suffered a traumatic brain injury.

Currently, over 270,000 military service members since 2000 and an estimated 1.7 million civilians in the US are affected by TBI, which often manifests as an inability to retrieve memories formed before being injured and an impaired ability to form new memories. Currently, there are also no effective treatments available, and beyond veterans, there are countless people around the world who suffer from the same condition as a result of accidents.

The teams will first develop computer models that describe how neurons code memories, as well as analyzing neural signals in order to understand how targeted stimulation might help restore the brain’s ability to form memories. The UCLA team will use data collected from epilepsy patients that already have electrodes implanted in their brains to develop a model of the hippocampal-entorhinal system – known to be involved in learning and memory.

Meanwhile, the University of Pennsylvania team will study neurosurgical patients with implanted brain electrodes, recording data as they play computer-based memory games in order to gain an understanding of how successful memory function works. All patients will be volunteers, and the teams then plan to integrate these models into implantable closed-loop systems.

Like the research on rats, the implant will pick up neural signals from an undamaged section of the brain and route it around the damaged portion, effectively forming a new neural link that functions as well as the undamaged brain. And this is not the only research that aims to help assist in memory function when it comes to veterans and those suffering from TBI.

At Lawrence Livermore National Labs (LLNL), for example, efforts are being made to create a new type of “memory bridge”. This research builds upon similar efforts from USC, where researcher Ted Berger developed the first implantable memory device (coincidentally, also as part of DARPA’s RAM program) where limited electrodes were applied to the hippocampal regions of the brain to assist in recall and memory formation.

However, until now, no research lab has had any real clue as to what kinds of “codes” are involved when applying electrical stimulus to the brain. The LLNL group, which previously contributed to the groundbreaking Argus II retinal prosthesis is now taking a more integrated approach. With the recent announcement of ample federal BRAIN Initiative funding, they aim to build multifunction electro-optical-chemical neural sensor-effectors.

On the electrical end, LLNL’s new wafer technology will use fairly high electrode counts (perhaps 500-1000 spots). Compared to the usual higher density 11,000-electrode chips that have been used in the past, these chips will have more sparsely distributed electrode locations. Integrated light guides will provide conduits for optogenetic manipulations, and as an added bonus bi-directional fluid channels for any number of chemical exchanges are also etched in.

And like their California/Penn colleagues, the LLNL has teamed up with DARPA to get the funding they need to make this project a reality. So far, DARPA funders have brought in the implant heavyweight Medtronic, which made news last year with the development of its own closed-loop stimulators, to lend its expertise. In their case, the stimulators merged Brain-Computer Interface (BCI) with Deep Brain Stimulation (DBS) to treat Parkinson’s.

Unfortunately, while immense progress in being made at the hardware end of things, there is still the matter of cracking the brains code first. In other words, where the device needs to be placed and which neurons need to be precisely controlled remain a mystery. Not all neurons are the same, and control hierarchies and preferred activation paths will inevitably emerge.

Ultimately, what is needed in order to make precisely-targeted deep brain stimulation (DBS) possible is a real 3D model of the regions of the brain involved. Multiple efforts are underway, not the least of which are the work of Michele Tagliati’s group from the Movement Disorders Program in the department of neurology at Cedars-Sinai, or the Human Brain Project in Luasanne, Switzerland.

In these and other cases, the use of MRIs and brain scans to create a working map of the human brain – so that attempts to create biomimetic prosthetics that can enhance or assist in it’s functions – is the ultimate goal. And once researchers have a better idea of what the brain’s layout is, and what kinds of control hierarchies and paths are involved, we can expect to see brain implants becoming a regular feature of medicine.

And as always, devices that can restore function also open the way for the possibility of enhancement. So we can also expect that bionics prosthetics that restore memory and cognitive function will give way to ones that boost these as well. The dream of Homo Superior, the post-human, or transhumanism – whatever you choose to call it – is looking to be increasingly within our grasp.

And be sure to check out this video from LLNL showcasing how their new neural implant works: